1 /* 2 * L2TP core. 3 * 4 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd 5 * 6 * This file contains some code of the original L2TPv2 pppol2tp 7 * driver, which has the following copyright: 8 * 9 * Authors: Martijn van Oosterhout <kleptog@svana.org> 10 * James Chapman (jchapman@katalix.com) 11 * Contributors: 12 * Michal Ostrowski <mostrows@speakeasy.net> 13 * Arnaldo Carvalho de Melo <acme@xconectiva.com.br> 14 * David S. Miller (davem@redhat.com) 15 * 16 * This program is free software; you can redistribute it and/or modify 17 * it under the terms of the GNU General Public License version 2 as 18 * published by the Free Software Foundation. 19 */ 20 21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 22 23 #include <linux/module.h> 24 #include <linux/string.h> 25 #include <linux/list.h> 26 #include <linux/rculist.h> 27 #include <linux/uaccess.h> 28 29 #include <linux/kernel.h> 30 #include <linux/spinlock.h> 31 #include <linux/kthread.h> 32 #include <linux/sched.h> 33 #include <linux/slab.h> 34 #include <linux/errno.h> 35 #include <linux/jiffies.h> 36 37 #include <linux/netdevice.h> 38 #include <linux/net.h> 39 #include <linux/inetdevice.h> 40 #include <linux/skbuff.h> 41 #include <linux/init.h> 42 #include <linux/in.h> 43 #include <linux/ip.h> 44 #include <linux/udp.h> 45 #include <linux/l2tp.h> 46 #include <linux/hash.h> 47 #include <linux/sort.h> 48 #include <linux/file.h> 49 #include <linux/nsproxy.h> 50 #include <net/net_namespace.h> 51 #include <net/netns/generic.h> 52 #include <net/dst.h> 53 #include <net/ip.h> 54 #include <net/udp.h> 55 #include <net/udp_tunnel.h> 56 #include <net/inet_common.h> 57 #include <net/xfrm.h> 58 #include <net/protocol.h> 59 #include <net/inet6_connection_sock.h> 60 #include <net/inet_ecn.h> 61 #include <net/ip6_route.h> 62 #include <net/ip6_checksum.h> 63 64 #include <asm/byteorder.h> 65 #include <linux/atomic.h> 66 67 #include "l2tp_core.h" 68 69 #define L2TP_DRV_VERSION "V2.0" 70 71 /* L2TP header constants */ 72 #define L2TP_HDRFLAG_T 0x8000 73 #define L2TP_HDRFLAG_L 0x4000 74 #define L2TP_HDRFLAG_S 0x0800 75 #define L2TP_HDRFLAG_O 0x0200 76 #define L2TP_HDRFLAG_P 0x0100 77 78 #define L2TP_HDR_VER_MASK 0x000F 79 #define L2TP_HDR_VER_2 0x0002 80 #define L2TP_HDR_VER_3 0x0003 81 82 /* L2TPv3 default L2-specific sublayer */ 83 #define L2TP_SLFLAG_S 0x40000000 84 #define L2TP_SL_SEQ_MASK 0x00ffffff 85 86 #define L2TP_HDR_SIZE_SEQ 10 87 #define L2TP_HDR_SIZE_NOSEQ 6 88 89 /* Default trace flags */ 90 #define L2TP_DEFAULT_DEBUG_FLAGS 0 91 92 /* Private data stored for received packets in the skb. 93 */ 94 struct l2tp_skb_cb { 95 u32 ns; 96 u16 has_seq; 97 u16 length; 98 unsigned long expires; 99 }; 100 101 #define L2TP_SKB_CB(skb) ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)]) 102 103 static struct workqueue_struct *l2tp_wq; 104 105 /* per-net private data for this module */ 106 static unsigned int l2tp_net_id; 107 struct l2tp_net { 108 struct list_head l2tp_tunnel_list; 109 spinlock_t l2tp_tunnel_list_lock; 110 struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2]; 111 spinlock_t l2tp_session_hlist_lock; 112 }; 113 114 #if IS_ENABLED(CONFIG_IPV6) 115 static bool l2tp_sk_is_v6(struct sock *sk) 116 { 117 return sk->sk_family == PF_INET6 && 118 !ipv6_addr_v4mapped(&sk->sk_v6_daddr); 119 } 120 #endif 121 122 static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk) 123 { 124 return sk->sk_user_data; 125 } 126 127 static inline struct l2tp_net *l2tp_pernet(const struct net *net) 128 { 129 BUG_ON(!net); 130 131 return net_generic(net, l2tp_net_id); 132 } 133 134 /* Session hash global list for L2TPv3. 135 * The session_id SHOULD be random according to RFC3931, but several 136 * L2TP implementations use incrementing session_ids. So we do a real 137 * hash on the session_id, rather than a simple bitmask. 138 */ 139 static inline struct hlist_head * 140 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id) 141 { 142 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)]; 143 144 } 145 146 /* Session hash list. 147 * The session_id SHOULD be random according to RFC2661, but several 148 * L2TP implementations (Cisco and Microsoft) use incrementing 149 * session_ids. So we do a real hash on the session_id, rather than a 150 * simple bitmask. 151 */ 152 static inline struct hlist_head * 153 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id) 154 { 155 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)]; 156 } 157 158 void l2tp_tunnel_free(struct l2tp_tunnel *tunnel) 159 { 160 sock_put(tunnel->sock); 161 /* the tunnel is freed in the socket destructor */ 162 } 163 EXPORT_SYMBOL(l2tp_tunnel_free); 164 165 /* Lookup a tunnel. A new reference is held on the returned tunnel. */ 166 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id) 167 { 168 const struct l2tp_net *pn = l2tp_pernet(net); 169 struct l2tp_tunnel *tunnel; 170 171 rcu_read_lock_bh(); 172 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 173 if (tunnel->tunnel_id == tunnel_id) { 174 l2tp_tunnel_inc_refcount(tunnel); 175 rcu_read_unlock_bh(); 176 177 return tunnel; 178 } 179 } 180 rcu_read_unlock_bh(); 181 182 return NULL; 183 } 184 EXPORT_SYMBOL_GPL(l2tp_tunnel_get); 185 186 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth) 187 { 188 const struct l2tp_net *pn = l2tp_pernet(net); 189 struct l2tp_tunnel *tunnel; 190 int count = 0; 191 192 rcu_read_lock_bh(); 193 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 194 if (++count > nth) { 195 l2tp_tunnel_inc_refcount(tunnel); 196 rcu_read_unlock_bh(); 197 return tunnel; 198 } 199 } 200 rcu_read_unlock_bh(); 201 202 return NULL; 203 } 204 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_nth); 205 206 /* Lookup a session. A new reference is held on the returned session. */ 207 struct l2tp_session *l2tp_session_get(const struct net *net, 208 struct l2tp_tunnel *tunnel, 209 u32 session_id) 210 { 211 struct hlist_head *session_list; 212 struct l2tp_session *session; 213 214 if (!tunnel) { 215 struct l2tp_net *pn = l2tp_pernet(net); 216 217 session_list = l2tp_session_id_hash_2(pn, session_id); 218 219 rcu_read_lock_bh(); 220 hlist_for_each_entry_rcu(session, session_list, global_hlist) { 221 if (session->session_id == session_id) { 222 l2tp_session_inc_refcount(session); 223 rcu_read_unlock_bh(); 224 225 return session; 226 } 227 } 228 rcu_read_unlock_bh(); 229 230 return NULL; 231 } 232 233 session_list = l2tp_session_id_hash(tunnel, session_id); 234 read_lock_bh(&tunnel->hlist_lock); 235 hlist_for_each_entry(session, session_list, hlist) { 236 if (session->session_id == session_id) { 237 l2tp_session_inc_refcount(session); 238 read_unlock_bh(&tunnel->hlist_lock); 239 240 return session; 241 } 242 } 243 read_unlock_bh(&tunnel->hlist_lock); 244 245 return NULL; 246 } 247 EXPORT_SYMBOL_GPL(l2tp_session_get); 248 249 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth) 250 { 251 int hash; 252 struct l2tp_session *session; 253 int count = 0; 254 255 read_lock_bh(&tunnel->hlist_lock); 256 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 257 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) { 258 if (++count > nth) { 259 l2tp_session_inc_refcount(session); 260 read_unlock_bh(&tunnel->hlist_lock); 261 return session; 262 } 263 } 264 } 265 266 read_unlock_bh(&tunnel->hlist_lock); 267 268 return NULL; 269 } 270 EXPORT_SYMBOL_GPL(l2tp_session_get_nth); 271 272 /* Lookup a session by interface name. 273 * This is very inefficient but is only used by management interfaces. 274 */ 275 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, 276 const char *ifname) 277 { 278 struct l2tp_net *pn = l2tp_pernet(net); 279 int hash; 280 struct l2tp_session *session; 281 282 rcu_read_lock_bh(); 283 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) { 284 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) { 285 if (!strcmp(session->ifname, ifname)) { 286 l2tp_session_inc_refcount(session); 287 rcu_read_unlock_bh(); 288 289 return session; 290 } 291 } 292 } 293 294 rcu_read_unlock_bh(); 295 296 return NULL; 297 } 298 EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname); 299 300 int l2tp_session_register(struct l2tp_session *session, 301 struct l2tp_tunnel *tunnel) 302 { 303 struct l2tp_session *session_walk; 304 struct hlist_head *g_head; 305 struct hlist_head *head; 306 struct l2tp_net *pn; 307 int err; 308 309 head = l2tp_session_id_hash(tunnel, session->session_id); 310 311 write_lock_bh(&tunnel->hlist_lock); 312 if (!tunnel->acpt_newsess) { 313 err = -ENODEV; 314 goto err_tlock; 315 } 316 317 hlist_for_each_entry(session_walk, head, hlist) 318 if (session_walk->session_id == session->session_id) { 319 err = -EEXIST; 320 goto err_tlock; 321 } 322 323 if (tunnel->version == L2TP_HDR_VER_3) { 324 pn = l2tp_pernet(tunnel->l2tp_net); 325 g_head = l2tp_session_id_hash_2(l2tp_pernet(tunnel->l2tp_net), 326 session->session_id); 327 328 spin_lock_bh(&pn->l2tp_session_hlist_lock); 329 330 hlist_for_each_entry(session_walk, g_head, global_hlist) 331 if (session_walk->session_id == session->session_id) { 332 err = -EEXIST; 333 goto err_tlock_pnlock; 334 } 335 336 l2tp_tunnel_inc_refcount(tunnel); 337 hlist_add_head_rcu(&session->global_hlist, g_head); 338 339 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 340 } else { 341 l2tp_tunnel_inc_refcount(tunnel); 342 } 343 344 hlist_add_head(&session->hlist, head); 345 write_unlock_bh(&tunnel->hlist_lock); 346 347 return 0; 348 349 err_tlock_pnlock: 350 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 351 err_tlock: 352 write_unlock_bh(&tunnel->hlist_lock); 353 354 return err; 355 } 356 EXPORT_SYMBOL_GPL(l2tp_session_register); 357 358 /***************************************************************************** 359 * Receive data handling 360 *****************************************************************************/ 361 362 /* Queue a skb in order. We come here only if the skb has an L2TP sequence 363 * number. 364 */ 365 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb) 366 { 367 struct sk_buff *skbp; 368 struct sk_buff *tmp; 369 u32 ns = L2TP_SKB_CB(skb)->ns; 370 371 spin_lock_bh(&session->reorder_q.lock); 372 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) { 373 if (L2TP_SKB_CB(skbp)->ns > ns) { 374 __skb_queue_before(&session->reorder_q, skbp, skb); 375 l2tp_dbg(session, L2TP_MSG_SEQ, 376 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n", 377 session->name, ns, L2TP_SKB_CB(skbp)->ns, 378 skb_queue_len(&session->reorder_q)); 379 atomic_long_inc(&session->stats.rx_oos_packets); 380 goto out; 381 } 382 } 383 384 __skb_queue_tail(&session->reorder_q, skb); 385 386 out: 387 spin_unlock_bh(&session->reorder_q.lock); 388 } 389 390 /* Dequeue a single skb. 391 */ 392 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb) 393 { 394 struct l2tp_tunnel *tunnel = session->tunnel; 395 int length = L2TP_SKB_CB(skb)->length; 396 397 /* We're about to requeue the skb, so return resources 398 * to its current owner (a socket receive buffer). 399 */ 400 skb_orphan(skb); 401 402 atomic_long_inc(&tunnel->stats.rx_packets); 403 atomic_long_add(length, &tunnel->stats.rx_bytes); 404 atomic_long_inc(&session->stats.rx_packets); 405 atomic_long_add(length, &session->stats.rx_bytes); 406 407 if (L2TP_SKB_CB(skb)->has_seq) { 408 /* Bump our Nr */ 409 session->nr++; 410 session->nr &= session->nr_max; 411 412 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n", 413 session->name, session->nr); 414 } 415 416 /* call private receive handler */ 417 if (session->recv_skb != NULL) 418 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length); 419 else 420 kfree_skb(skb); 421 } 422 423 /* Dequeue skbs from the session's reorder_q, subject to packet order. 424 * Skbs that have been in the queue for too long are simply discarded. 425 */ 426 static void l2tp_recv_dequeue(struct l2tp_session *session) 427 { 428 struct sk_buff *skb; 429 struct sk_buff *tmp; 430 431 /* If the pkt at the head of the queue has the nr that we 432 * expect to send up next, dequeue it and any other 433 * in-sequence packets behind it. 434 */ 435 start: 436 spin_lock_bh(&session->reorder_q.lock); 437 skb_queue_walk_safe(&session->reorder_q, skb, tmp) { 438 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) { 439 atomic_long_inc(&session->stats.rx_seq_discards); 440 atomic_long_inc(&session->stats.rx_errors); 441 l2tp_dbg(session, L2TP_MSG_SEQ, 442 "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n", 443 session->name, L2TP_SKB_CB(skb)->ns, 444 L2TP_SKB_CB(skb)->length, session->nr, 445 skb_queue_len(&session->reorder_q)); 446 session->reorder_skip = 1; 447 __skb_unlink(skb, &session->reorder_q); 448 kfree_skb(skb); 449 continue; 450 } 451 452 if (L2TP_SKB_CB(skb)->has_seq) { 453 if (session->reorder_skip) { 454 l2tp_dbg(session, L2TP_MSG_SEQ, 455 "%s: advancing nr to next pkt: %u -> %u", 456 session->name, session->nr, 457 L2TP_SKB_CB(skb)->ns); 458 session->reorder_skip = 0; 459 session->nr = L2TP_SKB_CB(skb)->ns; 460 } 461 if (L2TP_SKB_CB(skb)->ns != session->nr) { 462 l2tp_dbg(session, L2TP_MSG_SEQ, 463 "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n", 464 session->name, L2TP_SKB_CB(skb)->ns, 465 L2TP_SKB_CB(skb)->length, session->nr, 466 skb_queue_len(&session->reorder_q)); 467 goto out; 468 } 469 } 470 __skb_unlink(skb, &session->reorder_q); 471 472 /* Process the skb. We release the queue lock while we 473 * do so to let other contexts process the queue. 474 */ 475 spin_unlock_bh(&session->reorder_q.lock); 476 l2tp_recv_dequeue_skb(session, skb); 477 goto start; 478 } 479 480 out: 481 spin_unlock_bh(&session->reorder_q.lock); 482 } 483 484 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr) 485 { 486 u32 nws; 487 488 if (nr >= session->nr) 489 nws = nr - session->nr; 490 else 491 nws = (session->nr_max + 1) - (session->nr - nr); 492 493 return nws < session->nr_window_size; 494 } 495 496 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if 497 * acceptable, else non-zero. 498 */ 499 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb) 500 { 501 if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) { 502 /* Packet sequence number is outside allowed window. 503 * Discard it. 504 */ 505 l2tp_dbg(session, L2TP_MSG_SEQ, 506 "%s: pkt %u len %d discarded, outside window, nr=%u\n", 507 session->name, L2TP_SKB_CB(skb)->ns, 508 L2TP_SKB_CB(skb)->length, session->nr); 509 goto discard; 510 } 511 512 if (session->reorder_timeout != 0) { 513 /* Packet reordering enabled. Add skb to session's 514 * reorder queue, in order of ns. 515 */ 516 l2tp_recv_queue_skb(session, skb); 517 goto out; 518 } 519 520 /* Packet reordering disabled. Discard out-of-sequence packets, while 521 * tracking the number if in-sequence packets after the first OOS packet 522 * is seen. After nr_oos_count_max in-sequence packets, reset the 523 * sequence number to re-enable packet reception. 524 */ 525 if (L2TP_SKB_CB(skb)->ns == session->nr) { 526 skb_queue_tail(&session->reorder_q, skb); 527 } else { 528 u32 nr_oos = L2TP_SKB_CB(skb)->ns; 529 u32 nr_next = (session->nr_oos + 1) & session->nr_max; 530 531 if (nr_oos == nr_next) 532 session->nr_oos_count++; 533 else 534 session->nr_oos_count = 0; 535 536 session->nr_oos = nr_oos; 537 if (session->nr_oos_count > session->nr_oos_count_max) { 538 session->reorder_skip = 1; 539 l2tp_dbg(session, L2TP_MSG_SEQ, 540 "%s: %d oos packets received. Resetting sequence numbers\n", 541 session->name, session->nr_oos_count); 542 } 543 if (!session->reorder_skip) { 544 atomic_long_inc(&session->stats.rx_seq_discards); 545 l2tp_dbg(session, L2TP_MSG_SEQ, 546 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n", 547 session->name, L2TP_SKB_CB(skb)->ns, 548 L2TP_SKB_CB(skb)->length, session->nr, 549 skb_queue_len(&session->reorder_q)); 550 goto discard; 551 } 552 skb_queue_tail(&session->reorder_q, skb); 553 } 554 555 out: 556 return 0; 557 558 discard: 559 return 1; 560 } 561 562 /* Do receive processing of L2TP data frames. We handle both L2TPv2 563 * and L2TPv3 data frames here. 564 * 565 * L2TPv2 Data Message Header 566 * 567 * 0 1 2 3 568 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 569 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 570 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) | 571 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 572 * | Tunnel ID | Session ID | 573 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 574 * | Ns (opt) | Nr (opt) | 575 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 576 * | Offset Size (opt) | Offset pad... (opt) 577 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 578 * 579 * Data frames are marked by T=0. All other fields are the same as 580 * those in L2TP control frames. 581 * 582 * L2TPv3 Data Message Header 583 * 584 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 585 * | L2TP Session Header | 586 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 587 * | L2-Specific Sublayer | 588 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 589 * | Tunnel Payload ... 590 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 591 * 592 * L2TPv3 Session Header Over IP 593 * 594 * 0 1 2 3 595 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 596 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 597 * | Session ID | 598 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 599 * | Cookie (optional, maximum 64 bits)... 600 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 601 * | 602 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 603 * 604 * L2TPv3 L2-Specific Sublayer Format 605 * 606 * 0 1 2 3 607 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 608 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 609 * |x|S|x|x|x|x|x|x| Sequence Number | 610 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 611 * 612 * Cookie value and sublayer format are negotiated with the peer when 613 * the session is set up. Unlike L2TPv2, we do not need to parse the 614 * packet header to determine if optional fields are present. 615 * 616 * Caller must already have parsed the frame and determined that it is 617 * a data (not control) frame before coming here. Fields up to the 618 * session-id have already been parsed and ptr points to the data 619 * after the session-id. 620 */ 621 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, 622 unsigned char *ptr, unsigned char *optr, u16 hdrflags, 623 int length, int (*payload_hook)(struct sk_buff *skb)) 624 { 625 struct l2tp_tunnel *tunnel = session->tunnel; 626 int offset; 627 u32 ns, nr; 628 629 /* Parse and check optional cookie */ 630 if (session->peer_cookie_len > 0) { 631 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { 632 l2tp_info(tunnel, L2TP_MSG_DATA, 633 "%s: cookie mismatch (%u/%u). Discarding.\n", 634 tunnel->name, tunnel->tunnel_id, 635 session->session_id); 636 atomic_long_inc(&session->stats.rx_cookie_discards); 637 goto discard; 638 } 639 ptr += session->peer_cookie_len; 640 } 641 642 /* Handle the optional sequence numbers. Sequence numbers are 643 * in different places for L2TPv2 and L2TPv3. 644 * 645 * If we are the LAC, enable/disable sequence numbers under 646 * the control of the LNS. If no sequence numbers present but 647 * we were expecting them, discard frame. 648 */ 649 ns = nr = 0; 650 L2TP_SKB_CB(skb)->has_seq = 0; 651 if (tunnel->version == L2TP_HDR_VER_2) { 652 if (hdrflags & L2TP_HDRFLAG_S) { 653 ns = ntohs(*(__be16 *) ptr); 654 ptr += 2; 655 nr = ntohs(*(__be16 *) ptr); 656 ptr += 2; 657 658 /* Store L2TP info in the skb */ 659 L2TP_SKB_CB(skb)->ns = ns; 660 L2TP_SKB_CB(skb)->has_seq = 1; 661 662 l2tp_dbg(session, L2TP_MSG_SEQ, 663 "%s: recv data ns=%u, nr=%u, session nr=%u\n", 664 session->name, ns, nr, session->nr); 665 } 666 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 667 u32 l2h = ntohl(*(__be32 *) ptr); 668 669 if (l2h & 0x40000000) { 670 ns = l2h & 0x00ffffff; 671 672 /* Store L2TP info in the skb */ 673 L2TP_SKB_CB(skb)->ns = ns; 674 L2TP_SKB_CB(skb)->has_seq = 1; 675 676 l2tp_dbg(session, L2TP_MSG_SEQ, 677 "%s: recv data ns=%u, session nr=%u\n", 678 session->name, ns, session->nr); 679 } 680 ptr += 4; 681 } 682 683 if (L2TP_SKB_CB(skb)->has_seq) { 684 /* Received a packet with sequence numbers. If we're the LNS, 685 * check if we sre sending sequence numbers and if not, 686 * configure it so. 687 */ 688 if ((!session->lns_mode) && (!session->send_seq)) { 689 l2tp_info(session, L2TP_MSG_SEQ, 690 "%s: requested to enable seq numbers by LNS\n", 691 session->name); 692 session->send_seq = 1; 693 l2tp_session_set_header_len(session, tunnel->version); 694 } 695 } else { 696 /* No sequence numbers. 697 * If user has configured mandatory sequence numbers, discard. 698 */ 699 if (session->recv_seq) { 700 l2tp_warn(session, L2TP_MSG_SEQ, 701 "%s: recv data has no seq numbers when required. Discarding.\n", 702 session->name); 703 atomic_long_inc(&session->stats.rx_seq_discards); 704 goto discard; 705 } 706 707 /* If we're the LAC and we're sending sequence numbers, the 708 * LNS has requested that we no longer send sequence numbers. 709 * If we're the LNS and we're sending sequence numbers, the 710 * LAC is broken. Discard the frame. 711 */ 712 if ((!session->lns_mode) && (session->send_seq)) { 713 l2tp_info(session, L2TP_MSG_SEQ, 714 "%s: requested to disable seq numbers by LNS\n", 715 session->name); 716 session->send_seq = 0; 717 l2tp_session_set_header_len(session, tunnel->version); 718 } else if (session->send_seq) { 719 l2tp_warn(session, L2TP_MSG_SEQ, 720 "%s: recv data has no seq numbers when required. Discarding.\n", 721 session->name); 722 atomic_long_inc(&session->stats.rx_seq_discards); 723 goto discard; 724 } 725 } 726 727 /* Session data offset is defined only for L2TPv2 and is 728 * indicated by an optional 16-bit value in the header. 729 */ 730 if (tunnel->version == L2TP_HDR_VER_2) { 731 /* If offset bit set, skip it. */ 732 if (hdrflags & L2TP_HDRFLAG_O) { 733 offset = ntohs(*(__be16 *)ptr); 734 ptr += 2 + offset; 735 } 736 } 737 738 offset = ptr - optr; 739 if (!pskb_may_pull(skb, offset)) 740 goto discard; 741 742 __skb_pull(skb, offset); 743 744 /* If caller wants to process the payload before we queue the 745 * packet, do so now. 746 */ 747 if (payload_hook) 748 if ((*payload_hook)(skb)) 749 goto discard; 750 751 /* Prepare skb for adding to the session's reorder_q. Hold 752 * packets for max reorder_timeout or 1 second if not 753 * reordering. 754 */ 755 L2TP_SKB_CB(skb)->length = length; 756 L2TP_SKB_CB(skb)->expires = jiffies + 757 (session->reorder_timeout ? session->reorder_timeout : HZ); 758 759 /* Add packet to the session's receive queue. Reordering is done here, if 760 * enabled. Saved L2TP protocol info is stored in skb->sb[]. 761 */ 762 if (L2TP_SKB_CB(skb)->has_seq) { 763 if (l2tp_recv_data_seq(session, skb)) 764 goto discard; 765 } else { 766 /* No sequence numbers. Add the skb to the tail of the 767 * reorder queue. This ensures that it will be 768 * delivered after all previous sequenced skbs. 769 */ 770 skb_queue_tail(&session->reorder_q, skb); 771 } 772 773 /* Try to dequeue as many skbs from reorder_q as we can. */ 774 l2tp_recv_dequeue(session); 775 776 return; 777 778 discard: 779 atomic_long_inc(&session->stats.rx_errors); 780 kfree_skb(skb); 781 } 782 EXPORT_SYMBOL(l2tp_recv_common); 783 784 /* Drop skbs from the session's reorder_q 785 */ 786 int l2tp_session_queue_purge(struct l2tp_session *session) 787 { 788 struct sk_buff *skb = NULL; 789 BUG_ON(!session); 790 BUG_ON(session->magic != L2TP_SESSION_MAGIC); 791 while ((skb = skb_dequeue(&session->reorder_q))) { 792 atomic_long_inc(&session->stats.rx_errors); 793 kfree_skb(skb); 794 } 795 return 0; 796 } 797 EXPORT_SYMBOL_GPL(l2tp_session_queue_purge); 798 799 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame 800 * here. The skb is not on a list when we get here. 801 * Returns 0 if the packet was a data packet and was successfully passed on. 802 * Returns 1 if the packet was not a good data packet and could not be 803 * forwarded. All such packets are passed up to userspace to deal with. 804 */ 805 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb, 806 int (*payload_hook)(struct sk_buff *skb)) 807 { 808 struct l2tp_session *session = NULL; 809 unsigned char *ptr, *optr; 810 u16 hdrflags; 811 u32 tunnel_id, session_id; 812 u16 version; 813 int length; 814 815 /* UDP has verifed checksum */ 816 817 /* UDP always verifies the packet length. */ 818 __skb_pull(skb, sizeof(struct udphdr)); 819 820 /* Short packet? */ 821 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) { 822 l2tp_info(tunnel, L2TP_MSG_DATA, 823 "%s: recv short packet (len=%d)\n", 824 tunnel->name, skb->len); 825 goto error; 826 } 827 828 /* Trace packet contents, if enabled */ 829 if (tunnel->debug & L2TP_MSG_DATA) { 830 length = min(32u, skb->len); 831 if (!pskb_may_pull(skb, length)) 832 goto error; 833 834 pr_debug("%s: recv\n", tunnel->name); 835 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length); 836 } 837 838 /* Point to L2TP header */ 839 optr = ptr = skb->data; 840 841 /* Get L2TP header flags */ 842 hdrflags = ntohs(*(__be16 *) ptr); 843 844 /* Check protocol version */ 845 version = hdrflags & L2TP_HDR_VER_MASK; 846 if (version != tunnel->version) { 847 l2tp_info(tunnel, L2TP_MSG_DATA, 848 "%s: recv protocol version mismatch: got %d expected %d\n", 849 tunnel->name, version, tunnel->version); 850 goto error; 851 } 852 853 /* Get length of L2TP packet */ 854 length = skb->len; 855 856 /* If type is control packet, it is handled by userspace. */ 857 if (hdrflags & L2TP_HDRFLAG_T) { 858 l2tp_dbg(tunnel, L2TP_MSG_DATA, 859 "%s: recv control packet, len=%d\n", 860 tunnel->name, length); 861 goto error; 862 } 863 864 /* Skip flags */ 865 ptr += 2; 866 867 if (tunnel->version == L2TP_HDR_VER_2) { 868 /* If length is present, skip it */ 869 if (hdrflags & L2TP_HDRFLAG_L) 870 ptr += 2; 871 872 /* Extract tunnel and session ID */ 873 tunnel_id = ntohs(*(__be16 *) ptr); 874 ptr += 2; 875 session_id = ntohs(*(__be16 *) ptr); 876 ptr += 2; 877 } else { 878 ptr += 2; /* skip reserved bits */ 879 tunnel_id = tunnel->tunnel_id; 880 session_id = ntohl(*(__be32 *) ptr); 881 ptr += 4; 882 } 883 884 /* Find the session context */ 885 session = l2tp_session_get(tunnel->l2tp_net, tunnel, session_id); 886 if (!session || !session->recv_skb) { 887 if (session) 888 l2tp_session_dec_refcount(session); 889 890 /* Not found? Pass to userspace to deal with */ 891 l2tp_info(tunnel, L2TP_MSG_DATA, 892 "%s: no session found (%u/%u). Passing up.\n", 893 tunnel->name, tunnel_id, session_id); 894 goto error; 895 } 896 897 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook); 898 l2tp_session_dec_refcount(session); 899 900 return 0; 901 902 error: 903 /* Put UDP header back */ 904 __skb_push(skb, sizeof(struct udphdr)); 905 906 return 1; 907 } 908 909 /* UDP encapsulation receive handler. See net/ipv4/udp.c. 910 * Return codes: 911 * 0 : success. 912 * <0: error 913 * >0: skb should be passed up to userspace as UDP. 914 */ 915 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 916 { 917 struct l2tp_tunnel *tunnel; 918 919 tunnel = l2tp_tunnel(sk); 920 if (tunnel == NULL) 921 goto pass_up; 922 923 l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n", 924 tunnel->name, skb->len); 925 926 if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook)) 927 goto pass_up; 928 929 return 0; 930 931 pass_up: 932 return 1; 933 } 934 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv); 935 936 /************************************************************************ 937 * Transmit handling 938 ***********************************************************************/ 939 940 /* Build an L2TP header for the session into the buffer provided. 941 */ 942 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf) 943 { 944 struct l2tp_tunnel *tunnel = session->tunnel; 945 __be16 *bufp = buf; 946 __be16 *optr = buf; 947 u16 flags = L2TP_HDR_VER_2; 948 u32 tunnel_id = tunnel->peer_tunnel_id; 949 u32 session_id = session->peer_session_id; 950 951 if (session->send_seq) 952 flags |= L2TP_HDRFLAG_S; 953 954 /* Setup L2TP header. */ 955 *bufp++ = htons(flags); 956 *bufp++ = htons(tunnel_id); 957 *bufp++ = htons(session_id); 958 if (session->send_seq) { 959 *bufp++ = htons(session->ns); 960 *bufp++ = 0; 961 session->ns++; 962 session->ns &= 0xffff; 963 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n", 964 session->name, session->ns); 965 } 966 967 return bufp - optr; 968 } 969 970 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf) 971 { 972 struct l2tp_tunnel *tunnel = session->tunnel; 973 char *bufp = buf; 974 char *optr = bufp; 975 976 /* Setup L2TP header. The header differs slightly for UDP and 977 * IP encapsulations. For UDP, there is 4 bytes of flags. 978 */ 979 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 980 u16 flags = L2TP_HDR_VER_3; 981 *((__be16 *) bufp) = htons(flags); 982 bufp += 2; 983 *((__be16 *) bufp) = 0; 984 bufp += 2; 985 } 986 987 *((__be32 *) bufp) = htonl(session->peer_session_id); 988 bufp += 4; 989 if (session->cookie_len) { 990 memcpy(bufp, &session->cookie[0], session->cookie_len); 991 bufp += session->cookie_len; 992 } 993 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 994 u32 l2h = 0; 995 996 if (session->send_seq) { 997 l2h = 0x40000000 | session->ns; 998 session->ns++; 999 session->ns &= 0xffffff; 1000 l2tp_dbg(session, L2TP_MSG_SEQ, 1001 "%s: updated ns to %u\n", 1002 session->name, session->ns); 1003 } 1004 1005 *((__be32 *)bufp) = htonl(l2h); 1006 bufp += 4; 1007 } 1008 1009 return bufp - optr; 1010 } 1011 1012 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, 1013 struct flowi *fl, size_t data_len) 1014 { 1015 struct l2tp_tunnel *tunnel = session->tunnel; 1016 unsigned int len = skb->len; 1017 int error; 1018 1019 /* Debug */ 1020 if (session->send_seq) 1021 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes, ns=%u\n", 1022 session->name, data_len, session->ns - 1); 1023 else 1024 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes\n", 1025 session->name, data_len); 1026 1027 if (session->debug & L2TP_MSG_DATA) { 1028 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1029 unsigned char *datap = skb->data + uhlen; 1030 1031 pr_debug("%s: xmit\n", session->name); 1032 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, 1033 datap, min_t(size_t, 32, len - uhlen)); 1034 } 1035 1036 /* Queue the packet to IP for output */ 1037 skb->ignore_df = 1; 1038 #if IS_ENABLED(CONFIG_IPV6) 1039 if (l2tp_sk_is_v6(tunnel->sock)) 1040 error = inet6_csk_xmit(tunnel->sock, skb, NULL); 1041 else 1042 #endif 1043 error = ip_queue_xmit(tunnel->sock, skb, fl); 1044 1045 /* Update stats */ 1046 if (error >= 0) { 1047 atomic_long_inc(&tunnel->stats.tx_packets); 1048 atomic_long_add(len, &tunnel->stats.tx_bytes); 1049 atomic_long_inc(&session->stats.tx_packets); 1050 atomic_long_add(len, &session->stats.tx_bytes); 1051 } else { 1052 atomic_long_inc(&tunnel->stats.tx_errors); 1053 atomic_long_inc(&session->stats.tx_errors); 1054 } 1055 1056 return 0; 1057 } 1058 1059 /* If caller requires the skb to have a ppp header, the header must be 1060 * inserted in the skb data before calling this function. 1061 */ 1062 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len) 1063 { 1064 int data_len = skb->len; 1065 struct l2tp_tunnel *tunnel = session->tunnel; 1066 struct sock *sk = tunnel->sock; 1067 struct flowi *fl; 1068 struct udphdr *uh; 1069 struct inet_sock *inet; 1070 int headroom; 1071 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1072 int udp_len; 1073 int ret = NET_XMIT_SUCCESS; 1074 1075 /* Check that there's enough headroom in the skb to insert IP, 1076 * UDP and L2TP headers. If not enough, expand it to 1077 * make room. Adjust truesize. 1078 */ 1079 headroom = NET_SKB_PAD + sizeof(struct iphdr) + 1080 uhlen + hdr_len; 1081 if (skb_cow_head(skb, headroom)) { 1082 kfree_skb(skb); 1083 return NET_XMIT_DROP; 1084 } 1085 1086 /* Setup L2TP header */ 1087 session->build_header(session, __skb_push(skb, hdr_len)); 1088 1089 /* Reset skb netfilter state */ 1090 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 1091 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | 1092 IPSKB_REROUTED); 1093 nf_reset(skb); 1094 1095 bh_lock_sock(sk); 1096 if (sock_owned_by_user(sk)) { 1097 kfree_skb(skb); 1098 ret = NET_XMIT_DROP; 1099 goto out_unlock; 1100 } 1101 1102 /* The user-space may change the connection status for the user-space 1103 * provided socket at run time: we must check it under the socket lock 1104 */ 1105 if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) { 1106 kfree_skb(skb); 1107 ret = NET_XMIT_DROP; 1108 goto out_unlock; 1109 } 1110 1111 /* Get routing info from the tunnel socket */ 1112 skb_dst_drop(skb); 1113 skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0))); 1114 1115 inet = inet_sk(sk); 1116 fl = &inet->cork.fl; 1117 switch (tunnel->encap) { 1118 case L2TP_ENCAPTYPE_UDP: 1119 /* Setup UDP header */ 1120 __skb_push(skb, sizeof(*uh)); 1121 skb_reset_transport_header(skb); 1122 uh = udp_hdr(skb); 1123 uh->source = inet->inet_sport; 1124 uh->dest = inet->inet_dport; 1125 udp_len = uhlen + hdr_len + data_len; 1126 uh->len = htons(udp_len); 1127 1128 /* Calculate UDP checksum if configured to do so */ 1129 #if IS_ENABLED(CONFIG_IPV6) 1130 if (l2tp_sk_is_v6(sk)) 1131 udp6_set_csum(udp_get_no_check6_tx(sk), 1132 skb, &inet6_sk(sk)->saddr, 1133 &sk->sk_v6_daddr, udp_len); 1134 else 1135 #endif 1136 udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr, 1137 inet->inet_daddr, udp_len); 1138 break; 1139 1140 case L2TP_ENCAPTYPE_IP: 1141 break; 1142 } 1143 1144 l2tp_xmit_core(session, skb, fl, data_len); 1145 out_unlock: 1146 bh_unlock_sock(sk); 1147 1148 return ret; 1149 } 1150 EXPORT_SYMBOL_GPL(l2tp_xmit_skb); 1151 1152 /***************************************************************************** 1153 * Tinnel and session create/destroy. 1154 *****************************************************************************/ 1155 1156 /* Tunnel socket destruct hook. 1157 * The tunnel context is deleted only when all session sockets have been 1158 * closed. 1159 */ 1160 static void l2tp_tunnel_destruct(struct sock *sk) 1161 { 1162 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk); 1163 1164 if (tunnel == NULL) 1165 goto end; 1166 1167 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name); 1168 1169 /* Disable udp encapsulation */ 1170 switch (tunnel->encap) { 1171 case L2TP_ENCAPTYPE_UDP: 1172 /* No longer an encapsulation socket. See net/ipv4/udp.c */ 1173 (udp_sk(sk))->encap_type = 0; 1174 (udp_sk(sk))->encap_rcv = NULL; 1175 (udp_sk(sk))->encap_destroy = NULL; 1176 break; 1177 case L2TP_ENCAPTYPE_IP: 1178 break; 1179 } 1180 1181 /* Remove hooks into tunnel socket */ 1182 sk->sk_destruct = tunnel->old_sk_destruct; 1183 sk->sk_user_data = NULL; 1184 1185 /* Call the original destructor */ 1186 if (sk->sk_destruct) 1187 (*sk->sk_destruct)(sk); 1188 1189 kfree_rcu(tunnel, rcu); 1190 end: 1191 return; 1192 } 1193 1194 /* When the tunnel is closed, all the attached sessions need to go too. 1195 */ 1196 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel) 1197 { 1198 int hash; 1199 struct hlist_node *walk; 1200 struct hlist_node *tmp; 1201 struct l2tp_session *session; 1202 1203 BUG_ON(tunnel == NULL); 1204 1205 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n", 1206 tunnel->name); 1207 1208 write_lock_bh(&tunnel->hlist_lock); 1209 tunnel->acpt_newsess = false; 1210 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 1211 again: 1212 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) { 1213 session = hlist_entry(walk, struct l2tp_session, hlist); 1214 1215 l2tp_info(session, L2TP_MSG_CONTROL, 1216 "%s: closing session\n", session->name); 1217 1218 hlist_del_init(&session->hlist); 1219 1220 if (test_and_set_bit(0, &session->dead)) 1221 goto again; 1222 1223 write_unlock_bh(&tunnel->hlist_lock); 1224 1225 __l2tp_session_unhash(session); 1226 l2tp_session_queue_purge(session); 1227 1228 if (session->session_close != NULL) 1229 (*session->session_close)(session); 1230 1231 l2tp_session_dec_refcount(session); 1232 1233 write_lock_bh(&tunnel->hlist_lock); 1234 1235 /* Now restart from the beginning of this hash 1236 * chain. We always remove a session from the 1237 * list so we are guaranteed to make forward 1238 * progress. 1239 */ 1240 goto again; 1241 } 1242 } 1243 write_unlock_bh(&tunnel->hlist_lock); 1244 } 1245 EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall); 1246 1247 /* Tunnel socket destroy hook for UDP encapsulation */ 1248 static void l2tp_udp_encap_destroy(struct sock *sk) 1249 { 1250 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk); 1251 1252 if (tunnel) 1253 l2tp_tunnel_delete(tunnel); 1254 } 1255 1256 /* Workqueue tunnel deletion function */ 1257 static void l2tp_tunnel_del_work(struct work_struct *work) 1258 { 1259 struct l2tp_tunnel *tunnel = container_of(work, struct l2tp_tunnel, 1260 del_work); 1261 struct sock *sk = tunnel->sock; 1262 struct socket *sock = sk->sk_socket; 1263 struct l2tp_net *pn; 1264 1265 l2tp_tunnel_closeall(tunnel); 1266 1267 /* If the tunnel socket was created within the kernel, use 1268 * the sk API to release it here. 1269 */ 1270 if (tunnel->fd < 0) { 1271 if (sock) { 1272 kernel_sock_shutdown(sock, SHUT_RDWR); 1273 sock_release(sock); 1274 } 1275 } 1276 1277 /* Remove the tunnel struct from the tunnel list */ 1278 pn = l2tp_pernet(tunnel->l2tp_net); 1279 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1280 list_del_rcu(&tunnel->list); 1281 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1282 1283 /* drop initial ref */ 1284 l2tp_tunnel_dec_refcount(tunnel); 1285 1286 /* drop workqueue ref */ 1287 l2tp_tunnel_dec_refcount(tunnel); 1288 } 1289 1290 /* Create a socket for the tunnel, if one isn't set up by 1291 * userspace. This is used for static tunnels where there is no 1292 * managing L2TP daemon. 1293 * 1294 * Since we don't want these sockets to keep a namespace alive by 1295 * themselves, we drop the socket's namespace refcount after creation. 1296 * These sockets are freed when the namespace exits using the pernet 1297 * exit hook. 1298 */ 1299 static int l2tp_tunnel_sock_create(struct net *net, 1300 u32 tunnel_id, 1301 u32 peer_tunnel_id, 1302 struct l2tp_tunnel_cfg *cfg, 1303 struct socket **sockp) 1304 { 1305 int err = -EINVAL; 1306 struct socket *sock = NULL; 1307 struct udp_port_cfg udp_conf; 1308 1309 switch (cfg->encap) { 1310 case L2TP_ENCAPTYPE_UDP: 1311 memset(&udp_conf, 0, sizeof(udp_conf)); 1312 1313 #if IS_ENABLED(CONFIG_IPV6) 1314 if (cfg->local_ip6 && cfg->peer_ip6) { 1315 udp_conf.family = AF_INET6; 1316 memcpy(&udp_conf.local_ip6, cfg->local_ip6, 1317 sizeof(udp_conf.local_ip6)); 1318 memcpy(&udp_conf.peer_ip6, cfg->peer_ip6, 1319 sizeof(udp_conf.peer_ip6)); 1320 udp_conf.use_udp6_tx_checksums = 1321 ! cfg->udp6_zero_tx_checksums; 1322 udp_conf.use_udp6_rx_checksums = 1323 ! cfg->udp6_zero_rx_checksums; 1324 } else 1325 #endif 1326 { 1327 udp_conf.family = AF_INET; 1328 udp_conf.local_ip = cfg->local_ip; 1329 udp_conf.peer_ip = cfg->peer_ip; 1330 udp_conf.use_udp_checksums = cfg->use_udp_checksums; 1331 } 1332 1333 udp_conf.local_udp_port = htons(cfg->local_udp_port); 1334 udp_conf.peer_udp_port = htons(cfg->peer_udp_port); 1335 1336 err = udp_sock_create(net, &udp_conf, &sock); 1337 if (err < 0) 1338 goto out; 1339 1340 break; 1341 1342 case L2TP_ENCAPTYPE_IP: 1343 #if IS_ENABLED(CONFIG_IPV6) 1344 if (cfg->local_ip6 && cfg->peer_ip6) { 1345 struct sockaddr_l2tpip6 ip6_addr = {0}; 1346 1347 err = sock_create_kern(net, AF_INET6, SOCK_DGRAM, 1348 IPPROTO_L2TP, &sock); 1349 if (err < 0) 1350 goto out; 1351 1352 ip6_addr.l2tp_family = AF_INET6; 1353 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6, 1354 sizeof(ip6_addr.l2tp_addr)); 1355 ip6_addr.l2tp_conn_id = tunnel_id; 1356 err = kernel_bind(sock, (struct sockaddr *) &ip6_addr, 1357 sizeof(ip6_addr)); 1358 if (err < 0) 1359 goto out; 1360 1361 ip6_addr.l2tp_family = AF_INET6; 1362 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6, 1363 sizeof(ip6_addr.l2tp_addr)); 1364 ip6_addr.l2tp_conn_id = peer_tunnel_id; 1365 err = kernel_connect(sock, 1366 (struct sockaddr *) &ip6_addr, 1367 sizeof(ip6_addr), 0); 1368 if (err < 0) 1369 goto out; 1370 } else 1371 #endif 1372 { 1373 struct sockaddr_l2tpip ip_addr = {0}; 1374 1375 err = sock_create_kern(net, AF_INET, SOCK_DGRAM, 1376 IPPROTO_L2TP, &sock); 1377 if (err < 0) 1378 goto out; 1379 1380 ip_addr.l2tp_family = AF_INET; 1381 ip_addr.l2tp_addr = cfg->local_ip; 1382 ip_addr.l2tp_conn_id = tunnel_id; 1383 err = kernel_bind(sock, (struct sockaddr *) &ip_addr, 1384 sizeof(ip_addr)); 1385 if (err < 0) 1386 goto out; 1387 1388 ip_addr.l2tp_family = AF_INET; 1389 ip_addr.l2tp_addr = cfg->peer_ip; 1390 ip_addr.l2tp_conn_id = peer_tunnel_id; 1391 err = kernel_connect(sock, (struct sockaddr *) &ip_addr, 1392 sizeof(ip_addr), 0); 1393 if (err < 0) 1394 goto out; 1395 } 1396 break; 1397 1398 default: 1399 goto out; 1400 } 1401 1402 out: 1403 *sockp = sock; 1404 if ((err < 0) && sock) { 1405 kernel_sock_shutdown(sock, SHUT_RDWR); 1406 sock_release(sock); 1407 *sockp = NULL; 1408 } 1409 1410 return err; 1411 } 1412 1413 static struct lock_class_key l2tp_socket_class; 1414 1415 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp) 1416 { 1417 struct l2tp_tunnel *tunnel = NULL; 1418 int err; 1419 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; 1420 1421 if (cfg != NULL) 1422 encap = cfg->encap; 1423 1424 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL); 1425 if (tunnel == NULL) { 1426 err = -ENOMEM; 1427 goto err; 1428 } 1429 1430 tunnel->version = version; 1431 tunnel->tunnel_id = tunnel_id; 1432 tunnel->peer_tunnel_id = peer_tunnel_id; 1433 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS; 1434 1435 tunnel->magic = L2TP_TUNNEL_MAGIC; 1436 sprintf(&tunnel->name[0], "tunl %u", tunnel_id); 1437 rwlock_init(&tunnel->hlist_lock); 1438 tunnel->acpt_newsess = true; 1439 1440 if (cfg != NULL) 1441 tunnel->debug = cfg->debug; 1442 1443 tunnel->encap = encap; 1444 1445 refcount_set(&tunnel->ref_count, 1); 1446 tunnel->fd = fd; 1447 1448 /* Init delete workqueue struct */ 1449 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work); 1450 1451 INIT_LIST_HEAD(&tunnel->list); 1452 1453 err = 0; 1454 err: 1455 if (tunnelp) 1456 *tunnelp = tunnel; 1457 1458 return err; 1459 } 1460 EXPORT_SYMBOL_GPL(l2tp_tunnel_create); 1461 1462 static int l2tp_validate_socket(const struct sock *sk, const struct net *net, 1463 enum l2tp_encap_type encap) 1464 { 1465 if (!net_eq(sock_net(sk), net)) 1466 return -EINVAL; 1467 1468 if (sk->sk_type != SOCK_DGRAM) 1469 return -EPROTONOSUPPORT; 1470 1471 if ((encap == L2TP_ENCAPTYPE_UDP && sk->sk_protocol != IPPROTO_UDP) || 1472 (encap == L2TP_ENCAPTYPE_IP && sk->sk_protocol != IPPROTO_L2TP)) 1473 return -EPROTONOSUPPORT; 1474 1475 if (sk->sk_user_data) 1476 return -EBUSY; 1477 1478 return 0; 1479 } 1480 1481 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 1482 struct l2tp_tunnel_cfg *cfg) 1483 { 1484 struct l2tp_tunnel *tunnel_walk; 1485 struct l2tp_net *pn; 1486 struct socket *sock; 1487 struct sock *sk; 1488 int ret; 1489 1490 if (tunnel->fd < 0) { 1491 ret = l2tp_tunnel_sock_create(net, tunnel->tunnel_id, 1492 tunnel->peer_tunnel_id, cfg, 1493 &sock); 1494 if (ret < 0) 1495 goto err; 1496 } else { 1497 sock = sockfd_lookup(tunnel->fd, &ret); 1498 if (!sock) 1499 goto err; 1500 1501 ret = l2tp_validate_socket(sock->sk, net, tunnel->encap); 1502 if (ret < 0) 1503 goto err_sock; 1504 } 1505 1506 sk = sock->sk; 1507 1508 sock_hold(sk); 1509 tunnel->sock = sk; 1510 tunnel->l2tp_net = net; 1511 1512 pn = l2tp_pernet(net); 1513 1514 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1515 list_for_each_entry(tunnel_walk, &pn->l2tp_tunnel_list, list) { 1516 if (tunnel_walk->tunnel_id == tunnel->tunnel_id) { 1517 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1518 1519 ret = -EEXIST; 1520 goto err_sock; 1521 } 1522 } 1523 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list); 1524 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1525 1526 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 1527 struct udp_tunnel_sock_cfg udp_cfg = { 1528 .sk_user_data = tunnel, 1529 .encap_type = UDP_ENCAP_L2TPINUDP, 1530 .encap_rcv = l2tp_udp_encap_recv, 1531 .encap_destroy = l2tp_udp_encap_destroy, 1532 }; 1533 1534 setup_udp_tunnel_sock(net, sock, &udp_cfg); 1535 } else { 1536 sk->sk_user_data = tunnel; 1537 } 1538 1539 tunnel->old_sk_destruct = sk->sk_destruct; 1540 sk->sk_destruct = &l2tp_tunnel_destruct; 1541 lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, 1542 "l2tp_sock"); 1543 sk->sk_allocation = GFP_ATOMIC; 1544 1545 if (tunnel->fd >= 0) 1546 sockfd_put(sock); 1547 1548 return 0; 1549 1550 err_sock: 1551 if (tunnel->fd < 0) 1552 sock_release(sock); 1553 else 1554 sockfd_put(sock); 1555 err: 1556 return ret; 1557 } 1558 EXPORT_SYMBOL_GPL(l2tp_tunnel_register); 1559 1560 /* This function is used by the netlink TUNNEL_DELETE command. 1561 */ 1562 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) 1563 { 1564 if (!test_and_set_bit(0, &tunnel->dead)) { 1565 l2tp_tunnel_inc_refcount(tunnel); 1566 queue_work(l2tp_wq, &tunnel->del_work); 1567 } 1568 } 1569 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete); 1570 1571 /* Really kill the session. 1572 */ 1573 void l2tp_session_free(struct l2tp_session *session) 1574 { 1575 struct l2tp_tunnel *tunnel = session->tunnel; 1576 1577 BUG_ON(refcount_read(&session->ref_count) != 0); 1578 1579 if (tunnel) { 1580 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC); 1581 l2tp_tunnel_dec_refcount(tunnel); 1582 } 1583 1584 kfree(session); 1585 } 1586 EXPORT_SYMBOL_GPL(l2tp_session_free); 1587 1588 /* Remove an l2tp session from l2tp_core's hash lists. 1589 * Provides a tidyup interface for pseudowire code which can't just route all 1590 * shutdown via. l2tp_session_delete and a pseudowire-specific session_close 1591 * callback. 1592 */ 1593 void __l2tp_session_unhash(struct l2tp_session *session) 1594 { 1595 struct l2tp_tunnel *tunnel = session->tunnel; 1596 1597 /* Remove the session from core hashes */ 1598 if (tunnel) { 1599 /* Remove from the per-tunnel hash */ 1600 write_lock_bh(&tunnel->hlist_lock); 1601 hlist_del_init(&session->hlist); 1602 write_unlock_bh(&tunnel->hlist_lock); 1603 1604 /* For L2TPv3 we have a per-net hash: remove from there, too */ 1605 if (tunnel->version != L2TP_HDR_VER_2) { 1606 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1607 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1608 hlist_del_init_rcu(&session->global_hlist); 1609 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1610 synchronize_rcu(); 1611 } 1612 } 1613 } 1614 EXPORT_SYMBOL_GPL(__l2tp_session_unhash); 1615 1616 /* This function is used by the netlink SESSION_DELETE command and by 1617 pseudowire modules. 1618 */ 1619 int l2tp_session_delete(struct l2tp_session *session) 1620 { 1621 if (test_and_set_bit(0, &session->dead)) 1622 return 0; 1623 1624 __l2tp_session_unhash(session); 1625 l2tp_session_queue_purge(session); 1626 if (session->session_close != NULL) 1627 (*session->session_close)(session); 1628 1629 l2tp_session_dec_refcount(session); 1630 1631 return 0; 1632 } 1633 EXPORT_SYMBOL_GPL(l2tp_session_delete); 1634 1635 /* We come here whenever a session's send_seq, cookie_len or 1636 * l2specific_type parameters are set. 1637 */ 1638 void l2tp_session_set_header_len(struct l2tp_session *session, int version) 1639 { 1640 if (version == L2TP_HDR_VER_2) { 1641 session->hdr_len = 6; 1642 if (session->send_seq) 1643 session->hdr_len += 4; 1644 } else { 1645 session->hdr_len = 4 + session->cookie_len; 1646 session->hdr_len += l2tp_get_l2specific_len(session); 1647 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP) 1648 session->hdr_len += 4; 1649 } 1650 1651 } 1652 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len); 1653 1654 struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg) 1655 { 1656 struct l2tp_session *session; 1657 1658 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL); 1659 if (session != NULL) { 1660 session->magic = L2TP_SESSION_MAGIC; 1661 session->tunnel = tunnel; 1662 1663 session->session_id = session_id; 1664 session->peer_session_id = peer_session_id; 1665 session->nr = 0; 1666 if (tunnel->version == L2TP_HDR_VER_2) 1667 session->nr_max = 0xffff; 1668 else 1669 session->nr_max = 0xffffff; 1670 session->nr_window_size = session->nr_max / 2; 1671 session->nr_oos_count_max = 4; 1672 1673 /* Use NR of first received packet */ 1674 session->reorder_skip = 1; 1675 1676 sprintf(&session->name[0], "sess %u/%u", 1677 tunnel->tunnel_id, session->session_id); 1678 1679 skb_queue_head_init(&session->reorder_q); 1680 1681 INIT_HLIST_NODE(&session->hlist); 1682 INIT_HLIST_NODE(&session->global_hlist); 1683 1684 /* Inherit debug options from tunnel */ 1685 session->debug = tunnel->debug; 1686 1687 if (cfg) { 1688 session->pwtype = cfg->pw_type; 1689 session->debug = cfg->debug; 1690 session->mtu = cfg->mtu; 1691 session->mru = cfg->mru; 1692 session->send_seq = cfg->send_seq; 1693 session->recv_seq = cfg->recv_seq; 1694 session->lns_mode = cfg->lns_mode; 1695 session->reorder_timeout = cfg->reorder_timeout; 1696 session->l2specific_type = cfg->l2specific_type; 1697 session->cookie_len = cfg->cookie_len; 1698 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len); 1699 session->peer_cookie_len = cfg->peer_cookie_len; 1700 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len); 1701 } 1702 1703 if (tunnel->version == L2TP_HDR_VER_2) 1704 session->build_header = l2tp_build_l2tpv2_header; 1705 else 1706 session->build_header = l2tp_build_l2tpv3_header; 1707 1708 l2tp_session_set_header_len(session, tunnel->version); 1709 1710 refcount_set(&session->ref_count, 1); 1711 1712 return session; 1713 } 1714 1715 return ERR_PTR(-ENOMEM); 1716 } 1717 EXPORT_SYMBOL_GPL(l2tp_session_create); 1718 1719 /***************************************************************************** 1720 * Init and cleanup 1721 *****************************************************************************/ 1722 1723 static __net_init int l2tp_init_net(struct net *net) 1724 { 1725 struct l2tp_net *pn = net_generic(net, l2tp_net_id); 1726 int hash; 1727 1728 INIT_LIST_HEAD(&pn->l2tp_tunnel_list); 1729 spin_lock_init(&pn->l2tp_tunnel_list_lock); 1730 1731 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1732 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); 1733 1734 spin_lock_init(&pn->l2tp_session_hlist_lock); 1735 1736 return 0; 1737 } 1738 1739 static __net_exit void l2tp_exit_net(struct net *net) 1740 { 1741 struct l2tp_net *pn = l2tp_pernet(net); 1742 struct l2tp_tunnel *tunnel = NULL; 1743 int hash; 1744 1745 rcu_read_lock_bh(); 1746 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 1747 l2tp_tunnel_delete(tunnel); 1748 } 1749 rcu_read_unlock_bh(); 1750 1751 flush_workqueue(l2tp_wq); 1752 rcu_barrier(); 1753 1754 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1755 WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash])); 1756 } 1757 1758 static struct pernet_operations l2tp_net_ops = { 1759 .init = l2tp_init_net, 1760 .exit = l2tp_exit_net, 1761 .id = &l2tp_net_id, 1762 .size = sizeof(struct l2tp_net), 1763 }; 1764 1765 static int __init l2tp_init(void) 1766 { 1767 int rc = 0; 1768 1769 rc = register_pernet_device(&l2tp_net_ops); 1770 if (rc) 1771 goto out; 1772 1773 l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0); 1774 if (!l2tp_wq) { 1775 pr_err("alloc_workqueue failed\n"); 1776 unregister_pernet_device(&l2tp_net_ops); 1777 rc = -ENOMEM; 1778 goto out; 1779 } 1780 1781 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION); 1782 1783 out: 1784 return rc; 1785 } 1786 1787 static void __exit l2tp_exit(void) 1788 { 1789 unregister_pernet_device(&l2tp_net_ops); 1790 if (l2tp_wq) { 1791 destroy_workqueue(l2tp_wq); 1792 l2tp_wq = NULL; 1793 } 1794 } 1795 1796 module_init(l2tp_init); 1797 module_exit(l2tp_exit); 1798 1799 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 1800 MODULE_DESCRIPTION("L2TP core"); 1801 MODULE_LICENSE("GPL"); 1802 MODULE_VERSION(L2TP_DRV_VERSION); 1803 1804